It’s a group of Native American tribes that come together to help protect each other. What’s the hidden word (it’s 11 letters long)?

Can someone me with these questions plz.

Sally is making a model of a magnesium atom with an atomic mass number of 24 for her chemistry class. she has foam balls for the protons, neutrons, and electrons. she has added 6 neutrons to her model so far. how many more neutrons does she need to add to complete her neutral atom of magnesium?

Hey can you me with this i really need y’all